The use of fastening devices for the closure of containers, including plastic bag bodies, is generally known. Furthermore, the manufacture of closure fastening devices made of plastic materials is generally known to those skilled in the art relating to closure fastening devices as demonstrated by the numerous patents in this area.
A particularly well-known use for closure fastening devices is in connection with a flexible container, e.g., bag bodies. The closure fastening device and the associated container may be formed from thermoplastic materials. In addition, the closure fastening device and side walls of the container can be integrally formed by extrusion as a single piece, or may be formed as separate pieces and then connected by heat sealing or other suitable means.
The flexible containers are widely used to store and preserve food. The closure fastening devices allow the food to be stored in the air-tight flexible container. Although air-tight closure devices are preferred to preserve the food, it is difficult to exhaust air from the flexible container upon closure as noted in U.S. Pat. No. 4,532,652. In order to vent the air from the flexible container, the user must coordinate his or her movements. First, the flexible container which is filled with food is substantially, but not completely, closed. Second, the air is exhausted by pressing on the side walls of the bag. Finally, the bag is completely closed before a substantial amount of air reenters the bag. The movements required are cumbersome and are not easily performed by those lacking a high degree of dexterity and coordination. In addition, the bag is not sufficiently vented of the air which decreases the ability of the sealed bag to maintain food freshness.
Some storage bags have utilized a valve such as U.S. Pat. No. 4,532,652, or a venting structure such as U.S. Pat. No. 4,834,554, to allow air inside the bag to escape to the exterior of the bag. However, such devices are not able to permit the user to seal the bag in order to prevent further air from exiting or entering the bag, are more complicated and are more expensive to manufacture.